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Roads and trains were shut down across the New York area Monday night and into Tuesday, and for what? It snowed in New York, but only 9.8 inches fell in Central Park after predictions of a foot and a half or more. What went wrong? Forecasters, including yours truly, decided to go all-in on one weather model: the European model (or Euro).

And the Euro was way off. Other models had this storm pegged.1

Update after update, the Euro (produced by the European Center for Medium Range Weather Forecasting) kept predicting very high snow totals in New York. As of Monday morning’s run, the Euro was still projecting a foot and a half in the city. This consistency was too great for forecasters to ignore, especially because the Euro had been the first to jump on events such as the blizzard of 1996 and Hurricane Sandy. It also was one of the first to predict that a March 2001 storm was going to, like this one, be a bust. The Euro had a good track record.

That consistency, though, hid a great sense of uncertainty. The SREF (or Short-Range Ensemble Forecast), produced by the National Weather Service, collects 21 models (shown below). And Sunday night, the SREF indicated that the storm could be very different. Five of the 21 models in the SREF had (on a 10:1 snow-to-liquid ratio) less than 10 inches of snow falling. Nine of the 21 predicted a foot or less. Only eight could have been said to support 18 or more inches of snow in New York City.


In other words, 57 percent of the SREF members Sunday night suggested the forecasts were far too gung-ho. By Monday afternoon, 11 of the 21 members were on the 10-inches-or-less train. Eight of the 21 still supported big-time snow, but they were a minority.

The SREF members were not alone in being suspicious of so much snow. In Sunday’s 7 p.m. run, all of the other major models were against the Euro.

  • The American Global Forecasting System (GFS), which was recently upgraded, had only about 20 millimeters (or 8 inches of snow on a 10-to-1 ratio) falling for the storm. Although the GFS is considered inferior to the Euro by many meteorologists, the difference is probably overrated. Both models perform fairly well over the long term, as was pointed out in The New York Times this week. The GFS was showing the storm would stall too far northeast for New York to get the biggest snows. Instead, as we are seeing, those larger totals would be concentrated over Boston.
  • The GFS solution probably shouldn’t have been ignored given that it was joined by the Canadian’s global model, which had only 25 millimeters (or about 10 inches on a 10-to-1 ratio) falling as snow. The Canadian’s short-range model was slightly more pessimistic than the global. It predicted only about 20 to 25 millimeters (or 8 to 10 inches on a 10-to-1 ratio) of snow.
  • The United Kingdom’s model, which typically rates as the second-most accurate behind the Euro, was also on the little-snow train in New York. It had only 20 millimeters (or 8 inches on a 10-to-1 ratio) falling as snow.
  • Even the United States’ short-range North American Mesocale (NAM) model was on board with smaller accumulations, though it would change its tune in later runs and agree with the Euro for a time. On Sunday night, the NAM went with the 20 millimeters of snow.

Put it all together, and there was plenty of evidence this storm wouldn’t be record-setting in New York. Of course, forecasters are going to miss on occasion. Forecasting weather is very difficult. Models aren’t perfect, and forecasters should be practicing meteorology and not “modelology.”

That said, there are a few lessons to be learned:

  1. I’m not sure forecasters (including amateurs like myself) did a good enough job communicating to the public that there was great uncertainty in the forecast. This has been a problem for media forecasters who have historically been too confident in predicting precipitation events. A study of TV meteorologists in Kansas City found that when they predicted with 100 percent certainty that it would rain, it didn’t one-third of the time. Forecasters typically communicate margin of error by giving a range of outcomes (10 to 12 inches of snow, for example). In this instance, I don’t think the range adequately showed the disagreement among the models. Perhaps a probabilistic forecast is better.
  2. No model is infallible. Forecasters would have been better off averaging all the model data together, even the models that don’t have a stellar record. The Euro is king, but it’s not so good that we should ignore all other forecasts.
  3. There’s nothing wrong with changing a forecast. When the non-Euro models (except for the NAM) stayed consistent in showing about an inch or less of liquid precipitation (or 10 inches of snow on a 10-to-1 ratio) reaching New York and the Euro backed off its biggest predictions Monday afternoon, it was probably time for forecasters to change their stance. They waited too long; I’m not sure why.

Meteorology deals in probabilities and uncertainty. Models, and the forecasters who use those models, aren’t going to be perfect. In this case, there was a big storm. It just so happened to be confined to eastern Long Island and southern New England. But that’ll do little to satisfy New Yorkers who expected a historic blizzard.


And everything that is said about 7 day forecasts is so true – beyond 5 days, not worth shite! Might as well be +1!

Reposted from WattsUpWithThat.

Arctic blast coming to Eastern US – likely to be the coldest opening to calendar spring in at least 50 years

Another massive cold wave headed for Eastern US next week to put temperature 20 degrees below normal

Senior WeatherBell Meteorologist Joe Bastardi commented:

I am 58.. never seen anything close to this for late March.


[The] pattern next week has as much extreme potential for the time of the year as I can find. Coldest opening to calender spring in 50 yrs at least.

Weather forecast models such as the ECMWF and NCEP, both of which have had good track records this year in identifying polar vortex outbreaks in advance, are now forecasting a massive cold blast for the beginning of spring. See maps:


Dr. Ryan Maue commented on this forecast from ECMWF:

ECMWF 12z (WMO-Essential) 850-hPa temperature + wind streams. Final 10-day outcome after 2nd Arctic blast. Brutal.


He added:

Canadian ensemble system looks like other guidance at 7-days as well. This cake is baked. Arctic blast to end March

If Lake Michigan can open up a bit, then this cold could drop enormous amounts of Lake Effect snow on Lower Peninsula of Michigan.


2012-10-19: The massive cyclonic low churning over Lake Superior, coupled with the jetstream will funnel deep cold arctic air into the central US over the coming week. Fed by Pacific moisture, cold snowy conditions could be on the table for the upper Midwest states. There is enough energy here to channel that frigid arctic air right around to the central eastern states. Brrr!

Update 2010-02-02: As this major storm continues to track northeast, snow accumulations in southern Ontario will generally be less than anticipated in some areas due to the high ice, rain and sleet content of the precipitation from the warm sector of this massive extra-tropical cyclone. The cold front associated with the low will continue to produce cold snow over the Great Lakes region for the next 12-24 hours as the storm continues to feed moisture from the south into the circulation. Strong winds across the frontal boundaries will contribute to significant blowing snow and and lake effect snow in the lee areas of the Great Lakes for most of Wednesday, and as the snow pack chills, ground level whiteouts may be frequent in open areas.

A major storm system is expected to develop out of the central US and extend across southern Ontario and the US Northeast through Wednesday, February 3, 2011, bringing possible snowfall amounts to the lower Great Lakes basin in excess of 20 in. (50cm), with possible amounts to 18 in. (45cm). Forecast models are in good agreement as to the severity of the storm. This storm will be the first major storm for the GH-GTA; southwestern Ontario has already had record multi-day lake effect storms this winter.

This should be considered a dangerous winter storm. Heavy and blowing snow combined with a temperature of approximately -10C create a dangerous and life-threatening exposure risk.

The first panel below is the GFS model snow accumulation forecast through February 3, 2011,

and the following panel is the NAM 84hr forecast snow accumulation model. Both project anywhere from 30-45cm of snow for southwestern Ontario and the GH-GTA, and some lake effect enhancement is expected.

Environment Canada update, Saturday, Dec, 12, 2010 3:59PM

Special weather statement
Issued by Environment Canada Ontario region. 3:59 PM EST Saturday
11 December 2010.

Special weather statement issued for..
City of Toronto
Windsor – Essex – Chatham-Kent
Sarnia – Lambton
London – Middlesex
Simcoe – Delhi – Norfolk
Dunnville – Caledonia – Haldimand
Oxford – Brant
City of Hamilton
Halton – Peel
York – Durham
Huron – Perth
Waterloo – Wellington
Dufferin – Innisfil
Grey – Bruce
Barrie – Orillia – Midland
Belleville – Quinte – Northumberland
Kingston – Prince Edward
Peterborough – Kawartha Lakes
Stirling – Tweed – South Frontenac
Bancroft – Bon Echo Park
Brockville – Leeds and Grenville
City of Ottawa
Prescott and Russell
Cornwall – Morrisburg
Smiths Falls – Lanark – Sharbot Lake
Parry Sound – Muskoka
Renfrew – Pembroke – Barry’s Bay
Burk’s Falls – Bayfield Inlet.

Winter storm threatening Sunday into Monday..

A low pressure system over Iowa will track east towards the lower Great Lakes and will intensify into a winter storm by the time it reaches Western New York state by Sunday evening.

Precipitation associated with this system is expected to begin in Southwestern Ontario after midnight tonight.. Reaching the greater Toronto area and Eastern Ontario including the national Capital region by Sunday morning.

There is still some uncertainty with regard to its exact track and the type of precipitation associated over southern and Eastern Ontario as this messy low pressure system gets closer. If the low Pressure centre tracks further north than expected..The rain-snow
boundary will also shift north resulting in very little snow near the lower Great Lakes. However if the storm centre tracks further south Than expected..Heavier snow may become an issue for areas near lakes Erie and Ontario.

Latest indications suggest that in regions south of a line from about Sarnia through Vaughan to Cobourg..Precipitation will likely start Out as wet snow or a wet snow and rain mix..Possibly changing at times to rain Sunday. A changeover to all snow is expected Sunday evening as colder air starts to pump in from the north in the wake of the low. Snowfall accumulations are difficult to forecast at thisTime due to the rain versus snow problem..So a range of a couple cm near the Lake Erie and Lake Ontario shorelines to 10 to 15 cm of the white stuff in areas near the line is possible.

In regions southeast of a line from about Peterborough to Ottawa.. Precipitation will likely begin as snow..Then change to freezing rain Sunday morning or early Sunday afternoon. The precipitation will likely change over to rain Sunday evening in Eastern Ontario before
changing back to snow late in the evening or overnight again due to colder air starting to pump in from the north in the wake of the low. With freezing rain expected to be the main precipitation type, a freezing rain warning has been issued for Eastern Ontario and
snowfall accumulation are expected to be 5 cm or less.

North of a line from about Sarnia through Cobourg then northwest of a Line from Cobourg to Ottawa..Precipitation is expected to be mostly or all in the form of snow with significant amounts of 15 to 25 cm quite likely by Monday morning. A winter storm warning has been
issued for regions near and east of Georgian Bay as a result. As the winter storm moves northeast across Extreme Eastern Ontario into Québec Sunday night into Monday morning,. Strong north to northwest winds will develop in its wake. These winds will usher in much colder air and result in blowing snow in some areas by Monday.


Big Upcoming Snowstorm for the East?


By Meghan Evans, Meteorologist
Dec 5, 2010; 11:35 PM ET

Story has been updated 12/6/2010 2:00 pm….

Monster Storm Closes in on 50 Percent Snow Cover by Christmas

A storm that will take shape by the middle of December will cross the country and could end up developing into a major snowstorm for portions of the mid-Atlantic and New England.

There are different storm track scenarios at this point that mean the difference between mostly rain or a potential blizzard along the Interstate 95 corridor from Washington, D.C., to Boston.

So far, Chief Long Range Forecaster Joe Bastardi has been correct with the Winter Forecast for the Northeast with his prediction that late November to December would be cold and stormy for many.

According to Bastardi, “Repetitive cold waves and the threats of storms will keep hitting parts of the East in the weeks leading up to Christmas.”

“One or two of these storms has the potential to become a major snowstorm for portions of the mid-Atlantic and New England, including the storm that may hit the East from December 12-14.”

Expert Senior Meteorologist Henry Margusity has also been warning about how the cold pattern in the East could soon yield the season’s first major snowstorm.

Scenario One: Major Snowstorm for Interior Northeast

In the first scenario, the storm could cause significant snowfall and wind across portions of the Midwest and the Ohio Valley states, impacting places like St. Louis, Chicago, and Indianapolis.

The storm would then cut across the interior Northeast in the first scenario. Mild air would be drawn into the I-95 corridor, making it a rainstorm for the big Northeast cities.

Meanwhile, the interior Northeast, perhaps from Pittsburgh to Buffalo would get a dumping of heavy, disruptive snow, because this region would lie on the cold, northwestern edge of the storm.

Scenario Two: Major Snowstorm for Interstate 95 Corridor

“If the storm brushes up the Eastern Seaboard, several inches of snow could lead to major travel disruptions in the big cities from Washington, D.C. to Philadelphia and New York City to Boston,” according to Expert Senior Meteorologist Carl Erickson.

On top of heavy snowfall, blustery winds would add to this winter storm scenario by causing blowing snow and potential whiteout conditions at times.

Lake-effect snow to the lee of the Great Lakes would be likely to accompany this scenario as well with an arctic blast of air blowing across the relatively mild water of the Great Lakes.

Another Possibility

Erickson points out that there is one other possibility with this storm, stating “One other scenario is that the storm takes shape too far off the coast, which would promote a frigid, dry northwesterly flow of air into the Interstate 95 corridor. If this were to occur, there would be potential for even more heavy lake-effect snow downwind of the Great Lakes.”

A stalled low pressure system off the east coast of the Canadian Maritimes is being blamed for redirecting the jet stream, producing a steady cold polar flow of air out of the northwest across the Great Lakes region, resulting in steady accumulations of snow in the SE lee of the lakes. The wintry blast, which started at the tail end of last week, is not expected to abate before late Wednesday or early Thursday. Its not yet been determined whether records have been set yet, but portions of southwestern Ontario have received as much as 114cm of snow since the squall period began.

Lake effect snows occur when cold winds blow across the warm fall and early winter waters of the Great Lakes, picking up moisture. Once these winds come onshore, the air mass rises and cools, depositing the moisture as snow in the lee of the lakes. This is a surface effect. Most of these LES squalls are less than 12,000 feet in depth, and as a result, disappear from radar about 100/160km miles out from the radar site as the beam overshoots the snow deck. The Great Lakes region is prone to these squalls up until about February, when the lakes begin to freeze over much of their surface, depriving the wind of moisture. This transition can be seen as January skies change from cloudy and flurry, to clear and cold in early February.

The following two animations show the composite reflectivity pattern from KBUF in Buffalo, NY, showing the band alignment with the NW–>SE wind direction for december 5, 2010 and December 6, 2010, respectively. The darker the blue, the more intense the snow. Moist winds off Lake Huron and Georgian Bay in the upper left materialize as snow bands further enhanced by lakes Erie and Ontario as they cross into Ohio and New York State. The snow bands are largely continuous back to the upper lakes, but, are not seen because the radar beam has passed over top of the snow bands at the Lake Huron and Georgian Bay shorelines. (Click on animation image if animation doesn’t self start.)

The second animation for December 6, 2010 (cities layer is suppressed) shows the orographic (cooling as the moist air rises over landform) condensation into snow, in the second half of the animation as a crescent shaped band forming southeast of Georgian Bay, near the centre of the animation. The wind rises up the gentle slope of the Oak Ridges moraine, just above the north shore of Lake Ontario.

Environment Canada discussion:

Weather summary for all of Southern Ontario and the National Capital
Region issued by Environment Canada Toronto at 6:15 AM EST Tuesday
7 December 2010.

Significant lake effect snowfall reports.
==weather event discussion==

The traditional snow belts of Southern Ontario are in the midst of a
major multi-day snow squall event. Brisk northwest winds from Lake
Huron and Georgian Bay have produced impressive snowfall
accumulations over the past couple of days. Heavy snow squalls will
continue today and Wednesday likely giving remarkable snow totals
well over one metre in and around the London area as well as some
locales to the southeast of Georgian Bay.

Snowfall reports as of 6 PM Monday and fallen since Saturday night,
except for lucan which has received a staggering 114 cm as of
6 AM.
Location snowfall amounts (cm snow)

London 45-55
London aiport 53
Southeast of London 65-70
Lucan (northwest of London) 114
Dorchester (east of London) 42
Goderich 15-20
Mount Forest 10
Lakelet (near Clifford) 18
Paisley (ne of Kincardine) 5-10
Niagara 14
Toronto downtown 2-4
Toronto north 12
Newmarket 30
Maple 15-20
King City 20
Schomberg 33 as of 8 AM Monday
Beeton (south of Alliston) 81
Thornbury 40
Barrie 10-15

Please note that this summary contains the observations at the time
of broadcast and does not constitute an official and final report of
the weather events or the high impact events attributed to the
weather events.


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